1. Field of the Invention
The present invention relates to an organic thin film transistor (OTFT) having a patterned organic semiconductor layer designed to prevent damage to an underlying electrode wiring layer formed, and an organic light emitting display device including the OTFT.
2. Description of the Related Art
Active matrix (AM) organic light emitting display devices include a pixel circuit for each pixel. A pixel circuit is electrically connected to a scan line, a data line, and a power supply line and includes a thin film transistor (TFT) and a storage capacitor. Organic thin film transistors (OTFTs) use an organic layer as a semiconductor layer instead of using a silicon layer. OTFTs can operate at a low temperature and can be used as driving devices, and thus have been actively researched as possible switching elements of flexible organic light emitting display devices.
An organic light emitting display device that uses OTFTs as switching devices includes an organic semiconductor layer and a plurality of electrode wiring layers. When patterning the organic semiconductor layer, sometimes the underlying electrode wiring layers can be damaged. In particular, when patterning, sometimes source and drain electrodes of OTFTs can be damaged.
OTFTs include an organic semiconductor layer formed on the source and drain electrodes. In OTFTs, the organic semiconductor layer covers a portion of the source and drain electrodes because the organic semiconductor layer is patterned to form only a channel and not to completely cover the source and drain electrodes. Accordingly, when patterning an organic semiconductor layer of an OTFT, the organic semiconductor layer is blanket formed, and then parts of the organic semiconductor layer that will not become part of the channel are removed using a laser, etc. Since the source and drain electrodes and other electrode wiring layers can be damaged during this removal of the organic semiconductor layer, the OTFT can be defective. Therefore, what is needed is a design for a design for an OTFT and a design for a display using the same that does not result in a damaged electrode layer.